The Sudden Death in the Young (SDY) Initiative is a two-phase program to explore and provide greater understanding of SDY. The second phase of the program will support scientific research through the use of the registry data and DNA samples using the NIH grant mechanism. The second phase of the program will run concurrently with the SDY Registry. The SDY Registry has four objectives: Develop a surveillance system to comprehensively identify SDY cases for individuals up to 24 years of age in up to 15 states; Create a registry of clinical information about cases; Collect and store bio-specimens from registry cases; and Establish a resource that will be used by NHLBI-funded researchers to investigate SDY.